The Symbian Operating System is an advanced, open, standard operating system that is used for wireless computer and telephony. The Symbian OS includes sufficient flexibility and scalability to be used in a variety of mobile telephones having a wide range of particular user requirements.
The current platform security model in the Symbian OS provides capabilities for each binary component, particularly executable files having a .exe extension and dynamic link library files having a .dll extension. Capabilities are given by the operating system to the components at installation time. Client-server applicant program interfaces (API's) can check the capabilities of a calling process and determine if the calling process has a high enough capabilities to call the API. The capabilities of the calling process is determined by the executable code that has been used to create the calling process. A calling process cannot load components that have lower capabilities than what the calling process has itself.
The model described above has the problem that it is very difficult for the calling process to load a plug-in framework, which might consist of dozens of binary components with different capabilities. The plug-in framework is an important concept in Symbian OS.